Reverberation modulator for echo effect



July 2, 1946. M. PARISIER REVERBERATION MODULATOR FUR ECHO EFFECT FiledFeb. 26, 1944 EHTDE KNEW-Es;

FmEImSE EEEE' 'L wK a mu-M Mamas PARIS/El? INVENTOR ATTORNEY PatentedJuly" 2,

UNITED STATES I Prim-10m REVERBERATION MODfiLATOB FOR EGHO EFFECTMaurice Parisier, New York, N. Y. Application February 26, 1944, SerialNo. 524,037

My invention relates to reverberation modulators for echo efiect and hasparticular reference to devices for sound conditioning and for obtainingspecial sound effect for radio broadcasting and recording.

In my patent application, Serial No. 517,321, filed January 7, 1944, ofwhich this application is a continuation-in-part, I disclosed areverberation chamber in which sound is electrically reproduced,conditioned as to its reverberation and other properties, and againconverted into elec trical impulses for further broadcasting orrecording. I further disclosed means by which the volume of the chamberand the type of its walls can be" changed or modified for varying thereverberation and other sound effects.

For certain purposes it is also desired to produce an echo eiiect whenbroadcasting or record- .4 Claims." (01. Iva-4).

. whiching music, speech, singing, etc. My invention has for its object,therefore; to provide a chamber or chambers by means-of which echoefiect can be obtained. I

It is a well known fact that velocity of sound propagation varies withthe density of a'medium through which the sound is transmitted. In densemediums such as water, velocity of sound is greatly increased, and in ararefied air it is correspondingly reduced. According to my invention,therefore, it is possible to divide the sound impulses into severalfrequency bands or several channels with sound conditioning charg rhers, certain of these chambers transmitting the sound at a normal orincreased velocity, the other chambers beingadapted to retard the soundvelocity. This may be accomplished by using air at normal pressureor-compressing the air in high velocity chambers and exhausting the airto a desired degree in low velocity chambers, or by using other 7 gases.By combining the sound impulses received from the difierent chambers andmodulating Fig. 1 is a diagrammatic view of my system in which severalchannels or tracks are employed with various acoustic chambers, showingmeans for modulating the sound and for combining the tracks into asingle channel;

Fig. 2 is a sectional elevational view of my echo chamber;

Fig. 3 is a sectional plan view of the same.

My reverberation chamber or enclosure for producing echo effect is shownin Figs. 2 and 3 and consists of an outer shell I of a tubular shape,preferably made of a material having poor resonance properties such as aplastic or fibrous composition, suitably impregnated to make itairtight. The shell has flanges 2 at the end to which end covers 3 and 4are secured by screws or other suitable means. A tube 5 of a smalldiameter is fitted in the cover 3 with a valve 6 for exhausting the airfrom the space inside the shell or, if desired, for compressing the airor for filling the chamber inside with a suitable gas or vapor.

A loud speaker I is placed at one end of the chamber for convertingelectric impulses received through leads 8 into sound, and a microphoneI0 their relative intensities; it is possible to obtain loud principalsound with more or less weakened echoes in the form of sounds from thelow velocity chambers.

Another object of my invention is to prevent the sound in the lowvelocity chamber irom passing through the walls of the chamber, whichfor this purpose are lined with a soundproofing material and otherwiseso constructed as to inhibit the sound transmission. The soundtransmitters and receivers in the .chamber are for this purposesuspended on threads, wires, etc., so as to prevent direct transmissionof the sound to the walls or the chamber, restricting the soundtransmission II is placed at the other end of the chamber for convertingthe sound again into electric impulses.

To prevent direct transmission of sound through the walls of thechamber, the loud speaker and the microphone are suspended on wires orcords l2, IS. The walls for the same purpose are lined inside with asoundproofing material M such as rock wool, cotton, asbestos, etc., witha thin inner shell [5 preferably made also of a soundproofing materialsuch as fabric, leather, rubber, etc.

The enclosure or shell I may be of any suitable dimensions but need notbe very large so that several such enclosures can, be placed in a studiowhere the sound is produced or transmitted.

To obtain the echo efl'ect, the sound must be divided into severalchannels as shown in Fig.

1. Electric impulses from microphones 20 placed in a broadcasting orrecording! studio pass through switches II and through a common mixingamplifier 29 through regulating potentiometers 30, ill. These amplifierstransmit the sound directly, without my sound conditioning chambers.

The second set of the transmitting amplifiers 28 and filters I8 areconnected by lines 33 with loud speakers 1 in echo chambers orenclosures l, which may be tuned to different frequencies. The tuningmay be accomplished by varying dimensions of the chambers, by varyingthe relative angles of the loud speakers in addition to providingspecial filters 28 in the lines leading to the loud speakers.Potentiometers 26 or similar de-- vices are provided for regulating therelative intensities of the impulses for different loud speakers.

Microphones H are placed in front of the loud speakers and are connectedto receiving bus bars II by leads 4! at one side, and through regulatingpotentiometers 445, and leads 48 at the other side, the potentiometersbeing preferably placed at a common point of control.

Supplementary reverberation chambers may be also provided of a typedisclosed in my foregoing patent application, with provision for varyingthe volume of the chambers or the type of their walls.

The bus bars 4| are connected to a first mixing amplifier 80 which is inturn connected to the second or main mixing amplifier 29 through thepotentiometer 3|.

With my system it is possible to obtain various echo eflects. Thus, forinstance, it is possible to direct the low frequencies only through thefirst or direct channel, while sending the high frequencies through theecho chambers. By varying the relative intensities of the sound throughthese channels, a more or less strong echo effect may be obtained inconnection with sounds of higher lpitch. Or it may be possible to directall frequencies through the echo chambers, thereby obtaining echoefi'ect for all sounds. Usually it is preferred to have for everyfrequency band one direct and one echo channel so as to obtain directsound transmitted with a distinct accompanying echo.

It will be understood that various features and principles of each ofthe embodiments of the invention above described or referred to may beutilized or substituted in the other embodiments.

While the invention has been described in detail with respect to certainparticular preferred 4 examples, it will be understood by those sl llledin the art after understanding the invention, that various changes andfurther modifications may be made without departing from the spirit andscope of the invention, and it is intended therefore in the appendedclaims to cover all such changes and. modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. Means to obtain echo effect in sound transmission by radio comprisingmeans to separate electric impulses corresponding to the sounds to betransmitted into several channels of diiferent frequencies; means toconnect one channel directly to a receiver; means to individuallyregulate the impulses of the other channels; means to convert theimpulses of the other channels into secondary sounds; reverberationchambers in the paths of the secondary sounds; means to com vert thesounds of the second channel into secondary impulses; means ,toindividually regulate the secondary impulses; means to combine thesecondary impulses; means to regulate the combined secondary impulses;means to combine the secondary and primary impulses; and means toregulate the combined primary and secondary impulses.

2. A method of obtaining an echo effect in sound transmission by radioconsisting in separating electric impulses produced by a sound to betransmitted into groups of channels of different frequencies,transmitting the impulses of the first group of channels directly;individually regulating the impulses oi. the channels of the secondgroup; converting the impulses of the second group of channels intosecondary sounds; modifying the reverberation properties of thesecondary sounds; reconverting the secondary sounds into secondaryelectric impulses; regulating the secondary impulses, combining thesecondary impulses into one channel; regulating the combined secondaryimpulses; and-combining the impulses of the first group of channels withthe combined impulses of the second group.

3; A reverberation modulator comprising an air-tight enclosurecontaining a rarefied gas, means to produce sound in the enclosure, andmeans to receive sound within the enclosure and to convert it intoelectrical impulses.

4. A reverberation modulator comprising an air-tight enclosurecontaining a rarefied gas, means to produce sound in the enclosure,means to receive sound within the enclosure and to convert it intoelectrical impulses, and means for supporting at least one of theaforesaid means for angular adJustment to modify the sound effect withinthe enclosure.

MAURICE PARISIER.

